<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>3</title>
</head>
<body>
<!--变量声明符号: 1. let(常用) var-->
    <script>
      let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9];
      document.write(''+arr);
    </script>
</body>
</html>